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12.05.2026
You can easily calculate the storage run time using the formula: Run Time (hours) = Capacity (kWh) / Consumption (kW) × 0.9 (Efficiency). A 2 kWh storage unit like the SunEnergyXT BK215 PLUS from DRBO Greenenergy lasts approximately 18 hours with a consumption of 100 W (router + refrigerator), while a 10 kWh storage unit (expanded) lasts up to 90 hours. Practical examples and specific calculators for renter households, including 0% financing, can be found in this guide.
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What is the storage run time for balcony power storage units?
The storage run time – also referred to as autonomy – describes the period during which a balcony storage unit supplies your household appliances with electricity without additional power generation (e.g., at night or when cloudy). It depends on three factors: the usable capacity of the storage unit, the average power consumption, and the depth of discharge (DoD). DRBO Greenenergy's SunEnergyXT storage units use LiFePO4 batteries with a depth of discharge of 90 percent, thus offering maximum usable capacity. For example, a BK215 PLUS with 2.15 kWh nominal capacity provides approximately 1.94 kWh of usable energy.
How to calculate the storage run time accurately?
Step 1: Determine the usable capacity (nominal capacity × 0.9). Step 2: Determine your average power consumption in kilowatts. Step 3: Divide the usable capacity by the consumption. Example: BK215 PLUS (2.15 kWh) with 100 W consumption = 2.15 / 0.1 × 0.9 = 19.35 hours. The SunEnergyXT 500 PRO with 5 kWh nominal capacity achieves about 45 hours of run time with the same consumption. DRBO Greenenergy offers an interactive configurator on its website that automates these calculations and provides individual sizing recommendations.
| Consumption (Watts) | BK215 PLUS (2.15 kWh) | SunEnergyXT 500 PRO (5 kWh) | Expanded (10 kWh) |
|---|---|---|---|
| 50 W (Router) | ~38.7 h | ~90 h | ~180 h |
| 100 W (Router + Refrigerator) | ~19.4 h | ~45 h | ~90 h |
| 200 W (Household at night) | ~9.7 h | ~22.5 h | ~45 h |
| 500 W (Washing machine + Refrigerator) | ~3.9 h | ~9 h | ~18 h |
How long does a 2 kWh storage unit last in a renter's household?
A 2 kWh storage unit like the BK215 PLUS lasts a very long time in a typical renter's household. With an average night-time consumption of only 50 watts (router, LED lighting, refrigerator in standby), the storage unit supplies your household for about 36 hours. Even with 100 watts of consumption – realistic for a router, refrigerator, and a lamp – you can last a good 18 hours. The BK215 PLUS costs 749 Euros at DRBO Greenenergy and is Plug & Play, requiring no electrician installation. For renters with greater needs, combine the storage unit with a balcony power plant like the 900 Wp set for 269 Euros – together financeable with 0% interest.
How long does a 10 kWh storage unit last for a family household?
A 10 kWh storage unit – for example, by expanding two SunEnergyXT 500 PRO systems (5 kWh each) – supplies a family household with an average consumption of 500 watts for about 18 hours. With moderate consumption of 200 watts, it even lasts 45 hours. This sizing is particularly suitable for homeowners with dynamic electricity tariffs like Tibber or aWATTar, where the storage unit is charged at low electricity prices and used during expensive peak load times. DRBO Greenenergy offers the Dynamic Starter PLUS Set for 3,199 Euros – optimized for intelligent tariffs and automatic charging/discharging profiles via the SunEnergyXT App.
DRBO Greenenergy Expert Views
The right storage sizing is the key to maximum independence and cost savings. Our experience with over 10,000 installed systems shows: Renters benefit most from 2–5 kWh storage units in combination with 450–900 Wp balcony power plants, while homeowners should work with expandable systems like our SunEnergyXT 500 Pro. The decisive advantage of our storage units is the LiFePO4 chemistry with over 10,000 charge cycles – which means approximately 30 years of lifespan. Combined with the SunEnergyXT App, which provides real-time forecasts, you can plan your run time expectations precisely. Our German support team will help you free of charge with the optimal configuration – whether refurbished options for budget-conscious users or a fully expandable tower system up to 30 kWh.
Which devices does a balcony storage unit power for the longest?
The run time heavily depends on the individual device. A router with about 10 watts of consumption can power a 2 kWh storage unit for over 180 hours – more than 7 days. For a refrigerator with typically 80 watts of consumption (compressor runs intermittently), a 2 kWh storage unit lasts about 22.5 hours. Modern LED lighting with 5–10 watts per room allows run times of over 200 hours. A washing machine during a wash cycle (about 2 kW) empties a 2 kWh storage unit in just one hour. The trick: Combine time-insensitive consumers (refrigerator, router) with time-critical devices – this optimizes the total run time of your balcony power storage unit.
Why is storage sizing crucial for balcony power plants?
Incorrect sizing leads to two problems: Oversizing means unnecessary costs and space consumption, while undersizing results in frequent grid power consumption and thus a lack of cost savings. DRBO Greenenergy has therefore developed modular systems. Renters often start with a BK215 PLUS (2.15 kWh) and expand with B215 PLUS modules (2.15 kWh each) as needed. Homeowners choose the SunEnergyXT 500 series with up to 30 kWh total capacity through five B500 expansion modules. Precise calculation prevents investment waste and maximizes your annual electricity cost savings – an average of 70–150 Euros per month depending on household size and storage capacity.
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How to optimize run time with DRBO solutions?
DRBO Greenenergy offers several optimization approaches. First: Combine storage units with powerful balcony power plants – the 1800 Wp system with the BK215 PLUS ensures that you charge during the day and store in the evening. Second: Use intelligent control like the SunEnergyXT EV3600 bidirectional inverter (799 Euros), which charges and discharges the storage unit selectively. Third: Integrate zero export with the Shelly Pro 3EM – this way you optimally utilize every ray of sunshine. Fourth: Use the SunEnergyXT App with Home Assistant integration for real-time monitoring and precise run time forecasts. All these components are available from DRBO with 0% financing up to 2,500 Euros – spread over up to 36 months – and German support.
Can the storage run time be increased later?
Yes, absolutely. The modular concept of SunEnergyXT storage units from DRBO allows for easy retrofitting. The BK215 PLUS can be expanded with up to seven B215 PLUS modules – from 2.15 to a maximum of 17.2 kWh. The SunEnergyXT 500 PRO grows with up to four B500 expansion modules from 5 to 25 kWh. Installation is plug-and-play: connect cables, update battery management, done. This way, you start with a smaller budget and invest later when your living situation changes – ideal for growing families or renters moving into a home.
What are realistic run times in winter?
In winter, solar yield decreases significantly – often to 30–50% of summer performance. This means that while a balcony power plant fully charges your storage unit daily in summer, you usually need additional grid energy in winter. The run time of the storage unit itself remains the same, but you deplete it faster. A 5 kWh storage unit will still last you about 22.5 hours in winter with 200 watts of consumption – however, it will not be recharged by the solar panels. DRBO Greenenergy therefore recommends: Combine larger storage capacity (at least 5–10 kWh) with dynamic electricity tariffs. This way you charge cheap night-time electricity and use the storage unit during the day – regardless of weather and season.
How do temperature and age affect run time?
The LiFePO4 batteries in SunEnergyXT storage units are robust: they operate from -20 °C to +55 °C. In cold temperatures below 0 °C, the integrated battery heater activates automatically – this consumes some energy, but does not significantly reduce the run time. With increasing age, capacity gradually decreases: After 10,000 charge cycles (about 30 years), the residual capacity is still at least 80% of the original capacity. The practical consequence: a BK215 PLUS with 2.15 kWh will still retain about 1.72 kWh of usable capacity after 30 years. DRBO Greenenergy also offers refurbished storage units – tested used goods with a full warranty and thus an ideal entry-level option for price-conscious buyers.
Conclusion: Calculate and size storage run time correctly
The storage run time for balcony power plants is easy to calculate: Usable capacity divided by consumption gives the hours of autonomy. With DRBO Greenenergy, you will find the perfect sizing – from renter sets with 2 kWh (BK215 PLUS, 749 Euros) to flexible 5 kWh systems (SunEnergyXT 500 PRO, 1,349 Euros) to expandable tower solutions with up to 30 kWh. Free consultation helps you find exactly the right combination of storage unit, balcony power plant, and inverter. With 0% financing, a German support team, and a Trustpilot rating of 4.6/5, DRBO Greenenergy is your reliable partner for the decentralized energy transition.
Frequently Asked Questions about Storage Run Time
How long does a 2 kWh storage unit last for a refrigerator and router?
With an average consumption of 100 watts (router ~10 W + refrigerator ~80 W), a 2 kWh storage unit like the BK215 PLUS will supply you for about 18–20 hours. This is enough for a whole night plus a large part of the following morning, ideal for renters.
What affects storage run time the most?
The three main factors are: 1) Usable capacity (nominal capacity × 0.9), 2) average power consumption in watts, 3) ambient temperature and storage condition. The SunEnergyXT App from DRBO shows real-time forecasts based on your consumption patterns.
Is a 5 kWh storage unit suitable for dynamic electricity tariffs like Tibber?
Yes, perfectly. A 5 kWh storage unit like the SunEnergyXT 500 PRO (1,349 Euros) charges at low electricity prices at night and discharges during expensive peak times during the day. DRBO offers the Dynamic Starter PLUS Set (3,199 Euros) specifically for this application.
Are there balcony storage units with a long warranty and low price?
Yes, DRBO Greenenergy offers refurbished Minjet storage units (2,016 Wh) – tested used goods with a full warranty, significantly cheaper than new goods. With 0% financing, these are perfect for getting started.
Can I expand my storage unit later?
Absolutely. All SunEnergyXT systems from DRBO are modular: BK215 PLUS is expandable up to 17.2 kWh, SunEnergyXT 500 PRO up to 25 kWh. Start small, invest later – flexible and cost-conscious.
